학술논문
Upper limit on the $\eta\to\pi^{+}\pi^{-}$ branching fraction with the KLOE experiment
Document Type
Working Paper
Author
Babusci, D.; Berlowski, M.; Bloise, C.; Bossi, F.; Branchini, P.; Budano, A.; Cao, B.; Ceradini, F.; Ciambrone, P.; Curciarello, F.; Czerwiński, E.; D'Agostini, G.; Danè, E.; De Leo, V.; De Lucia, E.; De Santis, A.; De Simone, P.; Di Cicco, A.; Di Domenico, A.; Domenici, D.; D'Uffizi, A.; Fantini, A.; Fermani, P.; Fiore, S.; Gajos, A.; Gauzzi, P.; Giovannella, S.; Graziani, E.; Ivanov, V. L.; Johansson, T.; Kang, X.; Kisielewska-Kamińska, D.; Kozyrev, E. A.; Krzemien, W.; Kupsc, A.; Lukin, P. A.; Mandaglio, G.; Martini, M.; Messi, R.; Miscetti, S.; Moricciani, D.; Moskal, P.; Parzych, S.; Passeri, A.; Patera, V.; del Rio, E. Perez; Santangelo, P.; Schioppa, M.; Selce, A.; Silarski, M.; Sirghi, F.; Solodov, E. P.; Tortora, L.; Venanzoni, G.; Wiślicki, W.; Wolke, M.
Source
J. High Energ. Phys. 2020, 47 (2020)
Subject
Language
Abstract
Based on an integrated luminosity of 1.61 fb$^{-1}$ $e^+e^-$ collision data collected with the KLOE detector at DA$\Phi$NE, the Frascati $\phi$-factory, a search for the $P$- and $CP$-violating decay $\eta\to\pi^{+}\pi^{-}$ has been performed. Radiative $\phi\to\eta\gamma$ decay is exploited to access the $\eta$ mesons. No signal is observed in the $\pi^{+}\pi^{-}$ invariant mass spectrum, and the upper limit on the branching fraction at 90\% confidence level is determined to be ${\mathcal B}(\eta\to\pi^{+}\pi^{-})<4.9\times10^{-6}$, which is approximately three times smaller than the previous KLOE result. From the combination of these two measurements we get ${\mathcal B}(\eta\to\pi^{+}\pi^{-}) < 4.4\times10^{-6}$ at 90\% confidence level.
Comment: 11 pages, 3 figures
Comment: 11 pages, 3 figures